Hybrid Retrofit of Apple Carplay in 2009-2015 cars

Hi, I know I am in the wrong place but have recently got a 2009 Audi A4. This has no sat nav, just the Symphony stereo and I would like to install sat nav. The Alpine complete retrofit is over £1500 so the idea of simply overlaying carplay seems tempting. Searched the internet and this thread continually comes up as the most vocal and informative on the subject. Appreciate you are all A5 owners, but does anyone know if this solution will work for A4 and also if the China or RSNav options are the same as that sold by Unique Auto Developments in the uk? It looks and sounds the same though they claim to also include a touch screen overlay. Finally, does anyone know anywhere in or around North London that would install this? I know it is supposed to be plug and play but am not too keen on taking the car apart myself. Thanks for any advice.

Hi, have an issue on an A4 but hoping same as A5! I bought a kit from a local retailer who has since stopped trading but I think it came from Xcarlink (wired). Issue I have is that if I have bluetooth enabled on my mobile, I seem to be unable to take phone calls. I can see the call, get dialling tone and hear the person at the other end but they cannot hear me. If I disable bluetooth it works fine. I think when I first got it a couple of years ago this worked ok, but then after an apple update it stopped working. Hoping this is just a setting I have wrong, but any help really appreciated.